Ziyulu
Posts: 617
Joined: Thu Oct 13, 2016 10:35 am

Re: Did the 737 MAX go one step too far?

Wed Dec 12, 2018 1:50 pm

PlanesNTrains wrote:
PacificWest wrote:
PlanesNTrains wrote:

That would be the passenger. Vote with your wallets. As long as you (and I) make price the number one deciding factor, this is what you’ll get. And what is more “moral”, a bigger toilet or lower fares?


Somehow Airbus manages to be successful despite making a conscious effort to design aircraft with a cabin-width that prevents Airlines from compromising passenger comfort. The A320 cabin is 7" wider than the 737, and the A350 is 5" wider than the 787. I remember some article quoting SeatGuru that said if you average out the seat width across dozens of airlines, the average economy seat on an Airbus will be a half-inch wider than a Boeing.

I'll agree that the average person that flies 1-2x per year for holidays/vacation will purchase tickets purely on Price & Schedule, and they either don't care or have no clue what to expect when they board the plane. But the second one starts flying more than 7-8x per year, it doesn't take long to see recognize a pattern of narrow seats, long bathroom lines, and tiny lavs on Boeing's. When flying domestic, I'll pay 5-10% more per ticket to fly an A319/320/321 instead of taking a 737.


So we’re going to argue morality over a half-inch difference? Frankly I’d take a WN 737 over an NK A320 anyday. YMMV


What is the cabin width of a 737 vs. 757? Is it wider? Would seats be more comfortable in a 757?
 
B737900ER
Posts: 1028
Joined: Thu Aug 31, 2006 10:26 am

Re: Did the 737 MAX go one step too far?

Wed Dec 12, 2018 2:01 pm

Any airframe that is flown in an unairworthy condition is a step too far. Lion air pushed the pencil whip limit and got bit. Any flight control system on any aircraft that is flown around broken is dangerous regardless of training and design. Everyone wants to blame the design, but had lion air made an actual attempt at repair and repair confirmation we wouldn’t be having this discussion.
 
AvObserver
Posts: 2605
Joined: Sat Apr 06, 2002 7:40 am

Re: Did the 737 MAX go one step too far?

Wed Dec 12, 2018 2:23 pm

estorilm wrote:
Amiga500 wrote:
AvObserver wrote:
I hope posts like this put to rest the nonsense spewed by Airbus diehards that the MAX is fundamentally unstable despite that they offer no proof of such.


If it does not return from a non-stalled and within envelope positive angle of attack then it is longitudinally statically unstable by standard definitions of flight dynamics.

That in itself is no problem. Airbus have had relaxed stability aircraft for years with their FBW.


But direct law is direct law - you simply cannot have the FCS adding its own take on things when the pilots believe they are in total control.

THIS ^^^ I'd buy you a drink if I could.

NG STS augmentation is one thing, but MCAS going one step further? The damn airframe just simply wasn't designed to be compatible with engines this large, or providing such thrust. Blows my mind that Airbus can slap a huge efficient high BPR high thrust engine into a perfect CG location on the wing and have no (inherent) design/cg/stability issues, yet Boeing is forced to do ALL of this stuff and everyone STILL says they're perfectly identical aircraft that are basically each companies version of the same thing.

They aren't.

And you know more than the MAX pilots that have weighed in here and say it's NOT unstable? Unlikely.
 
AvObserver
Posts: 2605
Joined: Sat Apr 06, 2002 7:40 am

Re: Did the 737 MAX go one step too far?

Wed Dec 12, 2018 2:47 pm

WIederling wrote:
AvObserver wrote:
If pilots who actually fly the MAX say it's NOT unstable, I tend to believe them, ...


how much worth do you think is their statement?
Zero.
MCAS is a wrapper around the unpleasant pitch up behavior of the MAX.
( MCAS in a rather heavy handed way limits "real" AoA to stay inside the airframes even more limited save zone.)
As long as that works as expected nothing untowards happens.

Certification issue afaics is that if you ever stall the airframe it will stay stalled. afaik : not allowed.

Again, someone who thinks they know more than people who actually fly the airplane. It doesn't matter what your armchair analysis says against the opinion of those who fly the airplane in the real world. And knowing your bent, I'd say that weighs heavily against you having an objective argument. That the MCAS may have an issue needing to be addressed isn't in dispute but you haven't proved the MAX is unstable in flight. You are assuming that based on as yet incomplete data about the circumstances of the ill-fated flight and your own insistence that the LEAP engines greater weight and forward placement alter the plane's CoG so much it's fundamentally unstable. With the jury still out on the exact circumstances of the crash, we need to reserve judgement until ALL of the facts are in. In the meantime pilots who actually fly the MAX dispute your assertion.
 
Samrnpage
Posts: 555
Joined: Wed Mar 16, 2016 12:02 pm

Re: Did the 737 MAX go one step too far?

Wed Dec 12, 2018 2:56 pm

rbavfan wrote:
PlanesNTrains wrote:
Samrnpage wrote:
The MAX wasnt a step to far, the MAX 10 was though. The design is pushed so far that its got a weird MLG just to make sure it doesnt crash on takeoff.


I feel brain cells dying after reading this post.


Yeah he really does not get why the landing gear was modified, does he.


In hindsight i should have elaborated. Correct me if I am wrong but the MLG was done so the 10MAX would have sufficant runway performance without tailstriking? My point is it wouldnt work without the new MLG or they would overrun on takeoff or tail strike the moment there was a gust of wind on rotation. The 737 design cannot go further. They still have paper manuals to keep commonality for christ sake. The "797" should be a NSA family that has members going into the middle of the market like a "A322XLR" at the top end.
 
PlanesNTrains
Posts: 9527
Joined: Tue Feb 01, 2005 4:19 pm

Re: Did the 737 MAX go one step too far?

Wed Dec 12, 2018 3:08 pm

Samrnpage wrote:
rbavfan wrote:
PlanesNTrains wrote:

I feel brain cells dying after reading this post.


Yeah he really does not get why the landing gear was modified, does he.


In hindsight i should have elaborated. Correct me if I am wrong but the MLG was done so the 10MAX would have sufficant runway performance without tailstriking? My point is it wouldnt work without the new MLG or they would overrun on takeoff or tail strike the moment there was a gust of wind on rotation. The 737 design cannot go further. They still have paper manuals to keep commonality for christ sake. The "797" should be a NSA family that has members going into the middle of the market like a "A322XLR" at the top end.


There’s lots of things in modern airliners to “keep them from crashing...”. Tapered fuselage for “sufficient runway performance without tailstriking”, for example. Maybe I’m getting hung up on you getting hung up on landing gear design. It’s to improve performance and make the aircraft more versatile and appealing, not to keep it from crashing.
-Dave


MAX’d out on MAX threads. If you are starting a thread, and it’s about the MAX - stop. There’s already a thread that covers it.
 
parapente
Posts: 3061
Joined: Tue Mar 28, 2006 10:42 pm

Re: Did the 737 MAX go one step too far?

Wed Dec 12, 2018 3:11 pm

It's not that theMax10 wouldn't have worked,but it wouldn't have worked commercially.It would have needed too much runway,so...they made a major modification to the MLG so that it would work commercially-nothing wrong with that.But yes it does tell you (along with its range) that it the final iteration.Even now it does not have the capacity or range of an A321.Hence the MOM proposal.
But should they be building an NSA instead?Who knows.Lets see if they can close the business case for the present MOM797 or not.
What has been a constant theme however is that it is neigh on impossible to improve the 737/320 performance with a new conventional aircaft -assuming the same engines.
So to develop something that is truly superior something major has to happen.That would be ( for instance) a geared contra rotating open rotor turbine.RR/Safran have said the can overcome the noise issue ( in scale testing).Clearly then a new type of aircraft would be required to use them ( can't use underwing pods).So a big call from Boeing if they went down that route.
PS yes the 737 max is. Safe.
 
PlanesNTrains
Posts: 9527
Joined: Tue Feb 01, 2005 4:19 pm

Re: Did the 737 MAX go one step too far?

Wed Dec 12, 2018 3:21 pm

parapente wrote:
It's not that theMax10 wouldn't have worked,but it wouldn't have worked commercially.It would have needed too much runway,so...they made a major modification to the MLG so that it would work commercially-nothing wrong with that.But yes it does tell you (along with its range) that it the final iteration.Even now it does not have the capacity or range of an A321.Hence the MOM proposal.
But should they be building an NSA instead?Who knows.Lets see if they can close the business case for the present MOM797 or not.
What has been a constant theme however is that it is neigh on impossible to improve the 737/320 performance with a new conventional aircaft -assuming the same engines.
So to develop something that is truly superior something major has to happen.That would be ( for instance) a geared contra rotating open rotor turbine.RR/Safran have said the can overcome the noise issue ( in scale testing).Clearly then a new type of aircraft would be required to use them ( can't use underwing pods).So a big call from Boeing if they went down that route.
PS yes the 737 max is. Safe.


That’s the crux of it. People bash Boeing for not going clean sheet without acknowledging that a clean sheet absent some ground-breaking new technology (materials, manufacturing, power plant, etc) would cost $10-$15 BILLION and not be significantly better than the A320neo yet cost significantly more to purchase. They can’t have their cake and eat it too.

The MAX is making lemonade out of lemons. Nothing wrong with that if that’s the best option available. If the argument is that they should have done more to the MAX to improve on it, fine. Again I don’t think it reflects the market realities at the time but it’s a fair statement imho. That’s different than saying it’s a development too far. Airlines putting up twelve figures ($) of orders seems to say differently.
-Dave


MAX’d out on MAX threads. If you are starting a thread, and it’s about the MAX - stop. There’s already a thread that covers it.
 
ThePilot02
Posts: 1
Joined: Wed Dec 12, 2018 2:46 pm

Re: Did the 737 MAX go one step too far?

Wed Dec 12, 2018 3:28 pm

Well, I think that Boeing should have extended the fuselage of the 737 MAX 10 to 44 or to 45 meters and built center tanks for more capacity and more range. The airplane just had to be a bit higher so there can`t happen a tailstrike on takeoff. Or there should be the same landig gear like in the normal 737 MAX 10. Of course, it wouldn`t be a middle of the market airliner we are looking for. But it would be a good challenge for the A321neo LR which has met the 757-200 and for me, the products from Airbus are selling better...
 
catiii
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Re: Did the 737 MAX go one step too far?

Wed Dec 12, 2018 3:42 pm

WayexTDI wrote:
catiii wrote:
WayexTDI wrote:

OK, only ALPA pilots flying MAX is UA; how about SW Southwest Airlines Pilots Association:

Bottom line: it appears to be hit-or-miss, which is unacceptable.


No, bottom line is that you didn't read the context of the thread. The post I was responding to called the MCAS a "silent addition." I said it couldn't have been too silent, as UA trained on it (thusly they knew about it). You then said "UA ALPA seems to disagree" to which I pointed out the inaccuracy of your assertion.

Something you are obviously willing to not understand: that addition was silent to a certain number of airlines/pilots (as reported numerous times by numerous pilot groups) and was not disclosed to all.
If MCAS is that critical to flight safety (as it appears to be), then it must be disclosed to every single 737 MAX pilot, it must be part of the standard training, it must be disclosed in full.

One could always argue that the pilot unions are unions; meaning they will do everything to defend the undefendable (even if it means lying or bending the truth).
Fact is, Boeing has not refuted the claims that some pilots were not trained.; that says a lot.

catiii wrote:
Not sure what WN or AA have to do with any of the above but okay, unless you're trying to show that they didn't put in place the appropriate training? Have to wonder how UA and other carriers knew about it...

Because, last I checked, both WN & AA operate the MAX; and their pilot group have said they were not trained on the MCAS.
So, again, training is not uniform; which shouldn't have happened had Boeing made it clear the system was a critical part of flight safety.


Something you obviously willing to not understand: the post to which I replied said it was a silent addition. Full stop. The post never said silent to a "certain number of airlines and pilots."

Have you also considered the fact that it wasn't silent, and those carriers just never took the time to create training around it? It's curious that UA figured it out and no one else did...
 
PlanesNTrains
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Joined: Tue Feb 01, 2005 4:19 pm

Re: Did the 737 MAX go one step too far?

Wed Dec 12, 2018 4:10 pm

catiii wrote:
WayexTDI wrote:
catiii wrote:

No, bottom line is that you didn't read the context of the thread. The post I was responding to called the MCAS a "silent addition." I said it couldn't have been too silent, as UA trained on it (thusly they knew about it). You then said "UA ALPA seems to disagree" to which I pointed out the inaccuracy of your assertion.

Something you are obviously willing to not understand: that addition was silent to a certain number of airlines/pilots (as reported numerous times by numerous pilot groups) and was not disclosed to all.
If MCAS is that critical to flight safety (as it appears to be), then it must be disclosed to every single 737 MAX pilot, it must be part of the standard training, it must be disclosed in full.

One could always argue that the pilot unions are unions; meaning they will do everything to defend the undefendable (even if it means lying or bending the truth).
Fact is, Boeing has not refuted the claims that some pilots were not trained.; that says a lot.

catiii wrote:
Not sure what WN or AA have to do with any of the above but okay, unless you're trying to show that they didn't put in place the appropriate training? Have to wonder how UA and other carriers knew about it...

Because, last I checked, both WN & AA operate the MAX; and their pilot group have said they were not trained on the MCAS.
So, again, training is not uniform; which shouldn't have happened had Boeing made it clear the system was a critical part of flight safety.


Something you obviously willing to not understand: the post to which I replied said it was a silent addition. Full stop. The post never said silent to a "certain number of airlines and pilots."

Have you also considered the fact that it wasn't silent, and those carriers just never took the time to create training around it? It's curious that UA figured it out and no one else did...


Sometimes to get a special deal you need to ask the right questions. Perhaps in this case, in order to get the full information they needed to ask the right questions? Perhaps UA did? Pretty sad if that were the case.
-Dave


MAX’d out on MAX threads. If you are starting a thread, and it’s about the MAX - stop. There’s already a thread that covers it.
 
WIederling
Posts: 8673
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Re: Did the 737 MAX go one step too far?

Wed Dec 12, 2018 4:24 pm

AvObserver wrote:
With the jury still out on the exact circumstances of the crash, we need to reserve judgement until ALL of the facts are in. In the meantime pilots who actually fly the MAX dispute your assertion.

quite the long lament but no useful argument and some drive by smearing of the messenger.
( and it is not about CoG moving but about CoDrag changes)
This is more about physics, engineering and a bit of applied logic and less so about what people ( even pilots ) tell you.

MAX stability design issues are now a standalone problem. Lion Air ( making big or small errors or none at all ) just exposed the issue.
Last edited by WIederling on Wed Dec 12, 2018 4:41 pm, edited 1 time in total.
Murphy is an optimist
 
WayexTDI
Posts: 1162
Joined: Fri Sep 21, 2018 4:38 pm

Re: Did the 737 MAX go one step too far?

Wed Dec 12, 2018 4:32 pm

catiii wrote:
WayexTDI wrote:
catiii wrote:

No, bottom line is that you didn't read the context of the thread. The post I was responding to called the MCAS a "silent addition." I said it couldn't have been too silent, as UA trained on it (thusly they knew about it). You then said "UA ALPA seems to disagree" to which I pointed out the inaccuracy of your assertion.

Something you are obviously willing to not understand: that addition was silent to a certain number of airlines/pilots (as reported numerous times by numerous pilot groups) and was not disclosed to all.
If MCAS is that critical to flight safety (as it appears to be), then it must be disclosed to every single 737 MAX pilot, it must be part of the standard training, it must be disclosed in full.

One could always argue that the pilot unions are unions; meaning they will do everything to defend the undefendable (even if it means lying or bending the truth).
Fact is, Boeing has not refuted the claims that some pilots were not trained.; that says a lot.

catiii wrote:
Not sure what WN or AA have to do with any of the above but okay, unless you're trying to show that they didn't put in place the appropriate training? Have to wonder how UA and other carriers knew about it...

Because, last I checked, both WN & AA operate the MAX; and their pilot group have said they were not trained on the MCAS.
So, again, training is not uniform; which shouldn't have happened had Boeing made it clear the system was a critical part of flight safety.


Something you obviously willing to not understand: the post to which I replied said it was a silent addition. Full stop. The post never said silent to a "certain number of airlines and pilots."

Have you also considered the fact that it wasn't silent, and those carriers just never took the time to create training around it? It's curious that UA figured it out and no one else did...

Please explain how an airline is supposed to create a specific training program around something they are not aware about? How are they to ask about a system they've not been made aware of???
It's like if a judge is asking you to prove something doesn't exist...

Again, and for the last time since you cannot understand: if the system is that critical to the safety of flight, the information needed to have been flown down from Boeing to the airline/trainer without being asked. Full stop.
Because UA pilots were trained on it (good for them), it still does not absolve Boeing for not informing other airlines (such as WN or AA).
 
JoeCanuck
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Joined: Mon Dec 19, 2005 3:30 am

Re: Did the 737 MAX go one step too far?

Wed Dec 12, 2018 6:45 pm

WIederling wrote:
AvObserver wrote:
With the jury still out on the exact circumstances of the crash, we need to reserve judgement until ALL of the facts are in. In the meantime pilots who actually fly the MAX dispute your assertion.

quite the long lament but no useful argument and some drive by smearing of the messenger.
( and it is not about CoG moving but about CoDrag changes)
This is more about physics, engineering and a bit of applied logic and less so about what people ( even pilots ) tell you.

MAX stability design issues are now a standalone problem. Lion Air ( making big or small errors or none at all ) just exposed the issue.


Right...and I'm guessing that nobody on A.net knows exactly the extent of any MAX stability issues. So...any conclusion is, by definition, speculation...however that conclusion is reached.

Regulators around the world have universally concluded that whatever problems do exist, (including the ones exposed by the Lion Air accident), aren't serious enough to ground the fleet, so must not constitute a existential danger to the flying public.

That's not just pilots talking. That includes engineers, technicians and specialists with intimate knowledge of the MAX. So far, it looks like the only people calling the MAX inherently dangerous, post on A.net.

Airbus isn't even calling for the MAX's to be grounded so the plane can't be all bad.
What the...?
 
patches
Topic Author
Posts: 247
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Re: Did the 737 MAX go one step too far?

Wed Dec 12, 2018 8:03 pm

Thanks for all the feedback people. It just still seems weird that Boeing would not have been more transparent and trained those lion pilots on the new procedures on the Max. Even Southwest and American pilots questioned Boeing on not knowing all the procedures on how to disengage the new AOA system.
 
WayexTDI
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Joined: Fri Sep 21, 2018 4:38 pm

Re: Did the 737 MAX go one step too far?

Wed Dec 12, 2018 8:24 pm

patches wrote:
Thanks for all the feedback people. It just still seems weird that Boeing would not have been more transparent and trained those lion pilots on the new procedures on the Max. Even Southwest and American pilots questioned Boeing on not knowing all the procedures on how to disengage the new AOA system.

It doesn't matter.
According to some on here, since UA pilots were trained, Boeing is all clear; despite what WN and AA (at least) pilots say...
 
SPREE34
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Joined: Tue Jun 29, 2004 6:09 am

Re: Did the 737 MAX go one step too far?

Wed Dec 12, 2018 9:06 pm

Ziyulu wrote:
What is the cabin width of a 737 vs. 757? Is it wider? Would seats be more comfortable in a 757?


Same cross section.
I don't understand everything I don't know about this.
 
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7BOEING7
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Re: Did the 737 MAX go one step too far?

Wed Dec 12, 2018 10:19 pm

patches wrote:
Thanks for all the feedback people. It just still seems weird that Boeing would not have been more transparent and trained those lion pilots on the new procedures on the Max. Even Southwest and American pilots questioned Boeing on not knowing all the procedures on how to disengage the new AOA system.


Training???? Southwest and American pilots have been flying NG's around for years with a similar system (STS trims nose down as the airspeed decreases towards stall speed) that only has 2-3 sentences in the FCOM (that I'm guessing prior to the Lion Air accident most NG flight crews wouldn't remember if asked) and is not trained to in the simulator. IMHO the only training that will occur will be to emphasize to flight crews that if the stabilizer trim isn't behaving in a manner that benefits continued safe flight you turn the damn thing off.
 
kalvado
Posts: 1878
Joined: Wed Mar 01, 2006 4:29 am

Re: Did the 737 MAX go one step too far?

Wed Dec 12, 2018 10:26 pm

7BOEING7 wrote:
patches wrote:
Thanks for all the feedback people. It just still seems weird that Boeing would not have been more transparent and trained those lion pilots on the new procedures on the Max. Even Southwest and American pilots questioned Boeing on not knowing all the procedures on how to disengage the new AOA system.


Training???? Southwest and American pilots have been flying NG's around for years with a similar system (STS trims nose down as the airspeed decreases towards stall speed) that only has 2-3 sentences in the FCOM (that I'm guessing prior to the Lion Air accident most NG flight crews wouldn't remember if asked) and is not trained to in the simulator. IMHO the only training that will occur will be to emphasize to flight crews that if the stabilizer trim isn't behaving in a manner that benefits continued safe flight you turn the damn thing off.

One can only assume that STS was designed (programmed) properly, not by Ctrl-C - Ctrl-V of some code lines.
I understand reasoning behind not mentioning MCAS in training - but then it should be implemented properly for those reasons to be valid. And that is the scary part - I suspect Boeing on-board software was never independently audited . At least that is the way Toyota failed big time...
 
prebennorholm
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Re: Did the 737 MAX go one step too far?

Thu Dec 13, 2018 4:38 am

AvObserver wrote:
That the MCAS may have an issue needing to be addressed isn't in dispute but you haven't proved the MAX is unstable in flight. You are assuming that based on as yet incomplete data about the circumstances of the ill-fated flight and your own insistence that the LEAP engines greater weight and forward placement alter the plane's CoG so much it's fundamentally unstable.

Some of this discussion about stable / unstable is due to improper use of the English word "stable / unstable".

Put an egg on a table, lying on the side, rock the table, and the egg will sway a little from side to side. But as soon as you don't touch the table any longer, the egg will stop swaying. It is stable.

Put the egg on its end. Theoretically you may make it stand on the end, but as soon as you rock the table it will turn 90 degrees to its flatter side. On its end It is unstable.

Now put also a matchbox on the table, and rock the table. The egg will sway a little, while the matchbox will stay as glued to the table. The matchbox is stable. But is the egg now unstable?

No, the egg is as stable as before, but the matchbox has a larger stability margin. It will take more severe rocking of the table to make the matchbox turn over its end and fall on the floor than needed for the egg to do so.

All transport aircraft are stable on the pitch axis, also FBW. All aircraft, which are unstable on pitch, are military planes, and always FBW because the human brain isn't fast enough to control unstable flight. Their failure mode then isn't "alternate mode", but rather "ejection seat".

All transport aircraft must, to be certified, have a certain minimum level of stability margin.

In one certain corner of its flight envelope the 737MAX has a stability margin, which is lower than wanted, lower than the 737NG (commonality), or maybe even lower than demanded for certification. That is fully corrected by the MCAS system. It makes the MAX act exactly as if it was an NG.

The minimum stability margin must be maintained with CG all way from its forward to its backward limit. There is little doubt that a slight move forward of the back CG limit would have done the same trick. But it was hardly good PR to limit the CG range related to the NG.

The problem is that the MCAS software is another system which can fail. In the Lion Air case it failed because it was fed faulty input data. The crew could have saved the flight, but they failed to do so. Maybe because they didn't know about MCAS, maybe due to some other confusion. We will know more when we see the final report and/or the CVR data.

At the end of the day, for me it is a surprise that a plane, which is certified in the 21st century, has input to automatic primary flight control which is dependent on a single sensor, and "manual backup" with a second sensor, and not triple sensors with voting on agreement. Or at least automatic disconnection of automatic systems when the two sensors disagree. It seems rather "19th century" to me. I have seen plenty of examples of much better design throughout my 20th century lifeline.
Always keep your number of landings equal to your number of take-offs
 
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Jouhou
Posts: 1966
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Re: Did the 737 MAX go one step too far?

Thu Dec 13, 2018 9:06 am

crazyplane1234 wrote:
Jouhou wrote:
I really wish other passengers would rebel with me and choose flights on the standard amount of room and comfort a particular airline provides, not just cost. I scold my father for going for the cheapest possible flights and then complaining about shrinking spaces. I tell him he's a part of the problem by being a cheap-ass! It's okay to pay a little more to fly with the better airline.

It goes both ways. I personally wish for cheaper fares, but you don't see me scolding those who choose the more comfortable seats. Horses for courses.

It's okay to pay a little more to fly with the better airline, but it's equally okay to endure the worse airline to pay a little less.


Tiny lavatories aren't something people can escape by upgrading their seat. If an airline decides to inflict this upon their premium pax as well, that means people who won't take in consideration anything other than price are in fact inflicting their damage on everyone else.

Also airlines need to not do this. No. Unless you are some ultra bargain-bin airline, just please don't.
 
JoeCanuck
Posts: 4704
Joined: Mon Dec 19, 2005 3:30 am

Re: Did the 737 MAX go one step too far?

Thu Dec 13, 2018 9:37 am

prebennorholm wrote:
AvObserver wrote:
That the MCAS may have an issue needing to be addressed isn't in dispute but you haven't proved the MAX is unstable in flight. You are assuming that based on as yet incomplete data about the circumstances of the ill-fated flight and your own insistence that the LEAP engines greater weight and forward placement alter the plane's CoG so much it's fundamentally unstable.

Some of this discussion about stable / unstable is due to improper use of the English word "stable / unstable".

Put an egg on a table, lying on the side, rock the table, and the egg will sway a little from side to side. But as soon as you don't touch the table any longer, the egg will stop swaying. It is stable.

Put the egg on its end. Theoretically you may make it stand on the end, but as soon as you rock the table it will turn 90 degrees to its flatter side. On its end It is unstable.

Now put also a matchbox on the table, and rock the table. The egg will sway a little, while the matchbox will stay as glued to the table. The matchbox is stable. But is the egg now unstable?

No, the egg is as stable as before, but the matchbox has a larger stability margin. It will take more severe rocking of the table to make the matchbox turn over its end and fall on the floor than needed for the egg to do so.

All transport aircraft are stable on the pitch axis, also FBW. All aircraft, which are unstable on pitch, are military planes, and always FBW because the human brain isn't fast enough to control unstable flight. Their failure mode then isn't "alternate mode", but rather "ejection seat".

All transport aircraft must, to be certified, have a certain minimum level of stability margin.

In one certain corner of its flight envelope the 737MAX has a stability margin, which is lower than wanted, lower than the 737NG (commonality), or maybe even lower than demanded for certification. That is fully corrected by the MCAS system. It makes the MAX act exactly as if it was an NG.

The minimum stability margin must be maintained with CG all way from its forward to its backward limit. There is little doubt that a slight move forward of the back CG limit would have done the same trick. But it was hardly good PR to limit the CG range related to the NG.

The problem is that the MCAS software is another system which can fail. In the Lion Air case it failed because it was fed faulty input data. The crew could have saved the flight, but they failed to do so. Maybe because they didn't know about MCAS, maybe due to some other confusion. We will know more when we see the final report and/or the CVR data.

At the end of the day, for me it is a surprise that a plane, which is certified in the 21st century, has input to automatic primary flight control which is dependent on a single sensor, and "manual backup" with a second sensor, and not triple sensors with voting on agreement. Or at least automatic disconnection of automatic systems when the two sensors disagree. It seems rather "19th century" to me. I have seen plenty of examples of much better design throughout my 20th century lifeline.


There is a lot of really good stuff in that post. Well presented and interesting. Thanks.
What the...?
 
Amiga500
Posts: 2289
Joined: Tue Mar 03, 2015 8:22 am

Re: Did the 737 MAX go one step too far?

Thu Dec 13, 2018 11:31 am

AvObserver wrote:
If pilots who actually fly the MAX say it's NOT unstable, I tend to believe them,


I see in this (and subsequent posts) that you believe the sky-gods in the front to be infallible sources of knowledge on aircraft design and flight performance.

Would you be so quick to take the word of a taxi driver on how the engine ECU works over the word of an engineer that has designed said ECUs?

I'll repeat what I said:

"If it does not return from a non-stalled and within envelope positive angle of attack then it is longitudinally statically unstable by standard definitions of flight dynamics."

It is not my definition of flight dynamics that I am using - its industry standard. Furthermore, if the MAX was a completely stable aircraft throughout the flight envelope - then it wouldn't need the MCAS - unless you think Boeing doesn't know that the MAX is actually stable either?


prebennorholm makes a good point about relaxed stability - but if the MAX were relaxed stability to the point active control input is required to prevent departure from controlled flight - then while the static margin may be (just) negative aka stable and all is hunky dory on paper - its not really a stable aircraft.

At such edge of envelope conditions - performance can be so sensitive to outside perturbations at that condition that an adverse gust (for example) can lead to unstable conditions and departure from controlled flight. Hence why Boeing added the MCAS as a fudge around it - and cut more than a few corners putting it together.

As said above by prebennorholm as well - how a primary flight control system is allowed to be driven off one sensor is shocking in this day and age. How that isn't in large capital bolded red writing all over the FCOM is also unbelievable. Boeing have really had a dereliction of duty here.


I may be barking up the wrong tree - but it sounds like the powerpoint mafia and wordsmiths have "mitigated" their way out of paying for a solution (in terms of money, time and resource) by dancing around with words - and now nearly 200 people are dead because of it. Undue pressure from people that aren't knowledgeable enough to know better dictating over those that are is likely the root cause. Its a curse on engineering and not limited to any particular company, country or continent.
 
maint123
Posts: 175
Joined: Sun Nov 04, 2018 4:18 pm

Re: Did the 737 MAX go one step too far?

Thu Dec 13, 2018 2:49 pm

"Undue pressure from people that aren't knowledgeable enough to know better dictating over those that are is likely the root cause. Its a curse on engineering and not limited to any particular company, country or continent."

Well said. Seen it so often, people with no knowledge dictating changes and when things go wrong, washing their hands off it.
Boeing needs to be a Lot more transparent about the internal discussions they had about the changes in corporate in Max.
They have been errily quite about the whole tragedy.
 
catiii
Posts: 3117
Joined: Mon Mar 31, 2008 1:18 am

Re: Did the 737 MAX go one step too far?

Thu Dec 13, 2018 3:16 pm

WayexTDI wrote:
patches wrote:
Thanks for all the feedback people. It just still seems weird that Boeing would not have been more transparent and trained those lion pilots on the new procedures on the Max. Even Southwest and American pilots questioned Boeing on not knowing all the procedures on how to disengage the new AOA system.

It doesn't matter.
According to some on here, since UA pilots were trained, Boeing is all clear; despite what WN and AA (at least) pilots say...


I never said that. What I said, since reading comprehension clearly is not a strong suit of yours, is that the MCAS addition wasn't silent, because UA knew about it.

Simple as that. Try and keep up.
 
PlanesNTrains
Posts: 9527
Joined: Tue Feb 01, 2005 4:19 pm

Re: Did the 737 MAX go one step too far?

Thu Dec 13, 2018 3:21 pm

maint123 wrote:
"Undue pressure from people that aren't knowledgeable enough to know better dictating over those that are is likely the root cause. Its a curse on engineering and not limited to any particular company, country or continent."

Well said. Seen it so often, people with no knowledge dictating changes and when things go wrong, washing their hands off it.
Boeing needs to be a Lot more transparent about the internal discussions they had about the changes in corporate in Max.
They have been errily quite about the whole tragedy.


Just because they haven’t kept you in the loop of the investigation doesn’t mean they’ve been “eerily quiet”.
-Dave


MAX’d out on MAX threads. If you are starting a thread, and it’s about the MAX - stop. There’s already a thread that covers it.
 
WayexTDI
Posts: 1162
Joined: Fri Sep 21, 2018 4:38 pm

Re: Did the 737 MAX go one step too far?

Thu Dec 13, 2018 3:46 pm

catiii wrote:
WayexTDI wrote:
patches wrote:
Thanks for all the feedback people. It just still seems weird that Boeing would not have been more transparent and trained those lion pilots on the new procedures on the Max. Even Southwest and American pilots questioned Boeing on not knowing all the procedures on how to disengage the new AOA system.

It doesn't matter.
According to some on here, since UA pilots were trained, Boeing is all clear; despite what WN and AA (at least) pilots say...


I never said that. What I said, since reading comprehension clearly is not a strong suit of yours, is that the MCAS addition wasn't silent, because UA knew about it.

Simple as that. Try and keep up.

And obviously, Boeing did a great job communicating since everyone knew about it :roll:

Again, I said and repeated ad nauseum that Boeing did not communicate that new feature to everybody; doesn't mean that no one was aware of it, means some were not aware of it. It has been said by at least 2 US pilot unions.
 
smartplane
Posts: 1024
Joined: Fri Aug 03, 2018 9:23 pm

Re: Did the 737 MAX go one step too far?

Thu Dec 13, 2018 6:44 pm

AvObserver wrote:
If pilots who actually fly the MAX say it's NOT unstable, I tend to believe them, not the armchair experts who weigh in here tediously.

Which is valid, providing that in coming to this conclusion, they have turned off ALL the documented and undocumented assistance. And assuming that such can be turned off (for vehicles now, even in track day mode, even after removing fuses and relays, assistance continues, and/or reverts to limp mode - humans can no longer be trusted).

Maybe glass half full / empty, but interesting you state pilots say the MAX is not unstable, rather than the affirmative that it is stable, suggesting the definition of 'acceptable' stability has shifted towards the unstable end of the spectrum.
 
prebennorholm
Posts: 6954
Joined: Tue Mar 21, 2000 6:25 am

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 1:36 am

Amiga500 wrote:
prebennorholm makes a good point about relaxed stability - but if the MAX were relaxed stability to the point active control input is required to prevent departure from controlled flight - then while the static margin may be (just) negative aka stable and all is hunky dory on paper - its not really a stable aircraft.

I agree completely, also in the rest of your post #173. Anyway, my post #170 wasn't so much to discuss 737MAX stability, but more to attract attention to the fact that different users on this thread use the word "stable" differently and then begin shouting when they are misunderstood.

In my quote above you use the word "stable" twice (underlined by me) with two different meanings. First time it is about "absolute stability", while second "not stable" means a static margin which is lower than desireable.

The aerodynamic scientists have very complicated ways to deal with stability, and they describe it in ways which won't be understood by 99% on this forum. On this forum we must be more careful when we use the word to minimize misunderstandings.

It isn't just us who make different use of that s-word. USAF test pilot Chuck Yeager was a man of few words. When he tested the F-100 Super Sabre 65 years ago, then he wrote in his report: "It just ain't stable". He didn't mean "negative or relaxed stability", neither was he talking about "low static margin numbers". In that case the meaning was: "This plane is too sensitive to control to be a good and precise gun platform". Luckily the designers at the North American factories understood him and modified the plane accordingly.
Always keep your number of landings equal to your number of take-offs
 
AvObserver
Posts: 2605
Joined: Sat Apr 06, 2002 7:40 am

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 2:53 am

WIederling wrote:
AvObserver wrote:
With the jury still out on the exact circumstances of the crash, we need to reserve judgement until ALL of the facts are in. In the meantime pilots who actually fly the MAX dispute your assertion.

quite the long lament but no useful argument and some drive by smearing of the messenger.
( and it is not about CoG moving but about CoDrag changes)
This is more about physics, engineering and a bit of applied logic and less so about what people ( even pilots ) tell you.

MAX stability design issues are now a standalone problem. Lion Air ( making big or small errors or none at all ) just exposed the issue.

Okay, without the smear, again, you've alleged but not proven any such stability issues. You are making the assertion with theoretical claptrap but no actual facts to back it up. And you have the nerve to say that the opinions of MAX pilots who've chimed in here have no relevance. That sir, approaches the realm of arrogance. I've been plenty critical of Boeing's lack of candor on MCAS and I'm well aware that the 737 MAX design entails some compromises the newer A320NEO doesn't. But you've gone too far in branding the airplane "unstable' before all of the facts are in regarding the tragedy. If the investigation concludes that a fundamental stability issue was a contributing factor in the crash then I'll accept it. But until that time, I see you making a broad assumption you can't possibly back up with facts, especially in the face of denial from the pilots. Now unless those who've posted as MAX pilots are all liars, I fail to see how your argument holds up. Why don't you post the intricate data that led you to this conclusion because so far, in this thread, it looks a lot more like opinion instead of substance.
 
AvObserver
Posts: 2605
Joined: Sat Apr 06, 2002 7:40 am

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 3:24 am

Amiga500 wrote:
AvObserver wrote:
If pilots who actually fly the MAX say it's NOT unstable, I tend to believe them,


I see in this (and subsequent posts) that you believe the sky-gods in the front to be infallible sources of knowledge on aircraft design and flight performance.

Would you be so quick to take the word of a taxi driver on how the engine ECU works over the word of an engineer that has designed said ECUs?

I'll repeat what I said:

"If it does not return from a non-stalled and within envelope positive angle of attack then it is longitudinally statically unstable by standard definitions of flight dynamics."

It is not my definition of flight dynamics that I am using - its industry standard. Furthermore, if the MAX was a completely stable aircraft throughout the flight envelope - then it wouldn't need the MCAS - unless you think Boeing doesn't know that the MAX is actually stable either?

prebennorholm makes a good point about relaxed stability - but if the MAX were relaxed stability to the point active control input is required to prevent departure from controlled flight - then while the static margin may be (just) negative aka stable and all is hunky dory on paper - its not really a stable aircraft.

At such edge of envelope conditions - performance can be so sensitive to outside perturbations at that condition that an adverse gust (for example) can lead to unstable conditions and departure from controlled flight. Hence why Boeing added the MCAS as a fudge around it - and cut more than a few corners putting it together.

As said above by prebennorholm as well - how a primary flight control system is allowed to be driven off one sensor is shocking in this day and age. How that isn't in large capital bolded red writing all over the FCOM is also unbelievable. Boeing have really had a dereliction of duty here.

I may be barking up the wrong tree - but it sounds like the powerpoint mafia and wordsmiths have "mitigated" their way out of paying for a solution (in terms of money, time and resource) by dancing around with words - and now nearly 200 people are dead because of it. Undue pressure from people that aren't knowledgeable enough to know better dictating over those that are is likely the root cause. Its a curse on engineering and not limited to any particular company, country or continent.

Again, all of the facts are not in so it's still way to early to make such conclusions. You assume MCAS is needed to mitigate stability issues. How do you know why MCAS was added? Do you have a mole working at Boeing? And as for your definition: "If it does not return from a non-stalled and within envelope positive angle of attack then it is longitudinally statically unstable by standard definitions of flight dynamics." Do you know for certain this is what happened? Quite frankly, when you say don't take the pilots' word over an engineer's word, what do you know about the engineering of this airplane? Have the engineers come and indicted this design for instability? One thing at least I'd agree on, the MCAS itself may need to be fixed and that is a design issue, albeit probably one that won't take a great deal of time to remedy once they determine how the AOA sensors may have tripped it up. And it's still entirely possible that Lion Air's maintenance may have been complicit in the crash although, heaven forbid, I'm not ready to pronounce them guilty either. Boeing may have a faulty FCS though that too has yet to be proven and there's no denying they erred mightily in not properly announcing and documenting it for the pilots. That error is likely worth a big upcoming fine and possible loss of near-term sales campaigns but the pilots, assuming they're not imposters, are saying the MAX is stable in flight. So as I see it, you too are making a broad assumption which is a bridge too far. Perhaps you too could post some intricate data on just why the 737 MAX is "longitudinally statically unstable" and prove just why all of those assumed MAX pilots are so wrong when they insist it is stable. Enlighten us all!
 
WIederling
Posts: 8673
Joined: Sun Sep 13, 2015 2:15 pm

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 8:37 am

AvObserver wrote:
And you have the nerve to say that the opinions of MAX pilots who've chimed in here have no relevance. .................

Even longer lament.
Pilot opinion is worthless as they see the basic airframe wrapped by various enhancing systems ( including MCAS ).
Additionally they did not even know about MCAS.

Then it is not about complex computations or deeply fractal analysis.
It is all in the open.
MCAS appears to be designed to keep the plane below a distinct positive pitch up angle.
( in a rather anal retentive way )
That indicates that the stable range of attitudes ends there.
A stall recovery is deemed very difficult or even impossible.
IMU certification requirements do not allow this situation.
you can have relaxed stability ( but only in cruise?) but not positive feed back.
Murphy is an optimist
 
Ufsatp
Posts: 40
Joined: Wed May 24, 2017 6:21 pm

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 10:20 am

WayexTDI wrote:
catiii wrote:
WayexTDI wrote:
It doesn't matter.
According to some on here, since UA pilots were trained, Boeing is all clear; despite what WN and AA (at least) pilots say...


I never said that. What I said, since reading comprehension clearly is not a strong suit of yours, is that the MCAS addition wasn't silent, because UA knew about it.

Simple as that. Try and keep up.

And obviously, Boeing did a great job communicating since everyone knew about it :roll:

Again, I said and repeated ad nauseum that Boeing did not communicate that new feature to everybody; doesn't mean that no one was aware of it, means some were not aware of it. It has been said by at least 2 US pilot unions.


Does Boeing train airline pilots or do the individual airlines train their own pilots?
 
WIederling
Posts: 8673
Joined: Sun Sep 13, 2015 2:15 pm

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 10:46 am

Ufsatp wrote:
WayexTDI wrote:
catiii wrote:

I never said that. What I said, since reading comprehension clearly is not a strong suit of yours, is that the MCAS addition wasn't silent, because UA knew about it.

Simple as that. Try and keep up.

And obviously, Boeing did a great job communicating since everyone knew about it :roll:

Again, I said and repeated ad nauseum that Boeing did not communicate that new feature to everybody; doesn't mean that no one was aware of it, means some were not aware of it. It has been said by at least 2 US pilot unions.


Does Boeing train airline pilots or do the individual airlines train their own pilots?


Whatever. As the Manufacturer Boeing has to provide the basic curriculum.
Murphy is an optimist
 
Ufsatp
Posts: 40
Joined: Wed May 24, 2017 6:21 pm

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 11:15 am

WIederling wrote:
Ufsatp wrote:
WayexTDI wrote:
And obviously, Boeing did a great job communicating since everyone knew about it :roll:

Again, I said and repeated ad nauseum that Boeing did not communicate that new feature to everybody; doesn't mean that no one was aware of it, means some were not aware of it. It has been said by at least 2 US pilot unions.


Does Boeing train airline pilots or do the individual airlines train their own pilots?


Whatever. As the Manufacturer Boeing has to provide the basic curriculum.


It’s not whatever. Boeing has said they told the airlines about it. Look past your jealousy fueled hate of Boeing to see that.

“You may have seen media reports that we intentionally withheld information about airplane functionality from our customers. That’s simply untrue,” Muilenburg wrote. “The relevant function is described in the Flight Crew Operations Manual, and we routinely engage customers about how to operate our airplanes safely.”
 
WayexTDI
Posts: 1162
Joined: Fri Sep 21, 2018 4:38 pm

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 1:22 pm

Ufsatp wrote:
WIederling wrote:
Ufsatp wrote:

Does Boeing train airline pilots or do the individual airlines train their own pilots?


Whatever. As the Manufacturer Boeing has to provide the basic curriculum.


It’s not whatever. Boeing has said they told the airlines about it. Look past your jealousy fueled hate of Boeing to see that.

“You may have seen media reports that we intentionally withheld information about airplane functionality from our customers. That’s simply untrue,” Muilenburg wrote. “The relevant function is described in the Flight Crew Operations Manual, and we routinely engage customers about how to operate our airplanes safely.”

It's funny how some on here say we have to trust the MAX pilots when they say the MAX is not an unstable aircraft; yet, the same MAX pilots cannot be trusted when they say they were not made aware of the functioning of the MCAS system...
Kinda double standard, ain't it?

FWIW, I trust the pilots in what they are saying: the MAX is not inherently unstable, but some groups of pilots were kept in the dark(ish?) about the MCAS.
 
WIederling
Posts: 8673
Joined: Sun Sep 13, 2015 2:15 pm

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 1:39 pm

Ufsatp wrote:
“You may have seen media reports that we intentionally withheld information about airplane functionality from our customers. That’s simply untrue,” Muilenburg wrote. “The relevant function is described in the Flight Crew Operations Manual, and we routinely engage customers about how to operate our airplanes safely.”


Does this reference the current edition or the one before the crash?


Sorry I don't have access to your rose tinted B(TM) glasses.
Murphy is an optimist
 
kalvado
Posts: 1878
Joined: Wed Mar 01, 2006 4:29 am

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 2:07 pm

AvObserver wrote:
Amiga500 wrote:
AvObserver wrote:
If pilots who actually fly the MAX say it's NOT unstable, I tend to believe them,


I see in this (and subsequent posts) that you believe the sky-gods in the front to be infallible sources of knowledge on aircraft design and flight performance.

Would you be so quick to take the word of a taxi driver on how the engine ECU works over the word of an engineer that has designed said ECUs?

I'll repeat what I said:

"If it does not return from a non-stalled and within envelope positive angle of attack then it is longitudinally statically unstable by standard definitions of flight dynamics."

It is not my definition of flight dynamics that I am using - its industry standard. Furthermore, if the MAX was a completely stable aircraft throughout the flight envelope - then it wouldn't need the MCAS - unless you think Boeing doesn't know that the MAX is actually stable either?

prebennorholm makes a good point about relaxed stability - but if the MAX were relaxed stability to the point active control input is required to prevent departure from controlled flight - then while the static margin may be (just) negative aka stable and all is hunky dory on paper - its not really a stable aircraft.

At such edge of envelope conditions - performance can be so sensitive to outside perturbations at that condition that an adverse gust (for example) can lead to unstable conditions and departure from controlled flight. Hence why Boeing added the MCAS as a fudge around it - and cut more than a few corners putting it together.

As said above by prebennorholm as well - how a primary flight control system is allowed to be driven off one sensor is shocking in this day and age. How that isn't in large capital bolded red writing all over the FCOM is also unbelievable. Boeing have really had a dereliction of duty here.

I may be barking up the wrong tree - but it sounds like the powerpoint mafia and wordsmiths have "mitigated" their way out of paying for a solution (in terms of money, time and resource) by dancing around with words - and now nearly 200 people are dead because of it. Undue pressure from people that aren't knowledgeable enough to know better dictating over those that are is likely the root cause. Its a curse on engineering and not limited to any particular company, country or continent.

Again, all of the facts are not in so it's still way to early to make such conclusions. You assume MCAS is needed to mitigate stability issues. How do you know why MCAS was added? Do you have a mole working at Boeing? And as for your definition: "If it does not return from a non-stalled and within envelope positive angle of attack then it is longitudinally statically unstable by standard definitions of flight dynamics." Do you know for certain this is what happened? Quite frankly, when you say don't take the pilots' word over an engineer's word, what do you know about the engineering of this airplane? Have the engineers come and indicted this design for instability? One thing at least I'd agree on, the MCAS itself may need to be fixed and that is a design issue, albeit probably one that won't take a great deal of time to remedy once they determine how the AOA sensors may have tripped it up. And it's still entirely possible that Lion Air's maintenance may have been complicit in the crash although, heaven forbid, I'm not ready to pronounce them guilty either. Boeing may have a faulty FCS though that too has yet to be proven and there's no denying they erred mightily in not properly announcing and documenting it for the pilots. That error is likely worth a big upcoming fine and possible loss of near-term sales campaigns but the pilots, assuming they're not imposters, are saying the MAX is stable in flight. So as I see it, you too are making a broad assumption which is a bridge too far. Perhaps you too could post some intricate data on just why the 737 MAX is "longitudinally statically unstable" and prove just why all of those assumed MAX pilots are so wrong when they insist it is stable. Enlighten us all!

This all started from the Leeham article on MCAS, and I was the one to bring up the instability issue here.
Leeham gives a (IMHO very plausible) explanation of instability mechanisms and reasons MCAS was implemented.
If you want argue - go find the article, read it, and then we may talk.
 
User avatar
glideslope
Posts: 1547
Joined: Sun May 30, 2004 8:06 pm

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 2:28 pm

B737900ER wrote:
Any airframe that is flown in an unairworthy condition is a step too far. Lion air pushed the pencil whip limit and got bit. Any flight control system on any aircraft that is flown around broken is dangerous regardless of training and design. Everyone wants to blame the design, but had lion air made an actual attempt at repair and repair confirmation we wouldn’t be having this discussion.


I could not agree more strongly.
To know your Enemy, you must become your Enemy.” Sun Tzu
 
kalvado
Posts: 1878
Joined: Wed Mar 01, 2006 4:29 am

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 2:35 pm

glideslope wrote:
B737900ER wrote:
Any airframe that is flown in an unairworthy condition is a step too far. Lion air pushed the pencil whip limit and got bit. Any flight control system on any aircraft that is flown around broken is dangerous regardless of training and design. Everyone wants to blame the design, but had lion air made an actual attempt at repair and repair confirmation we wouldn’t be having this discussion.


I could not agree more strongly.

Would you also agree that Any airframe that is flown in an uncertifiable condition is a step too far?
 
TranscendZac
Posts: 133
Joined: Sat Jun 13, 2015 12:50 pm

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 3:03 pm

Stitch wrote:
WIederling wrote:
Randy Boeing and his PR backoffice isn't really the source for any balanced or even god forbid neutral information. Try again.


And yet no outrage for all the Airbus PR charts posted by a certain Belgian with a Diptera infestation. :scratchchin: :rotfl:

Drosophila melanogaster? :lol:
Zac
 
PlanesNTrains
Posts: 9527
Joined: Tue Feb 01, 2005 4:19 pm

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 3:37 pm

kalvado wrote:
glideslope wrote:
B737900ER wrote:
Any airframe that is flown in an unairworthy condition is a step too far. Lion air pushed the pencil whip limit and got bit. Any flight control system on any aircraft that is flown around broken is dangerous regardless of training and design. Everyone wants to blame the design, but had lion air made an actual attempt at repair and repair confirmation we wouldn’t be having this discussion.


I could not agree more strongly.

Would you also agree that Any airframe that is flown in an uncertifiable condition is a step too far?


Too far and done poorly would seem to be two different things.
-Dave


MAX’d out on MAX threads. If you are starting a thread, and it’s about the MAX - stop. There’s already a thread that covers it.
 
B737900ER
Posts: 1028
Joined: Thu Aug 31, 2006 10:26 am

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 4:22 pm

WayexTDI wrote:

FWIW, I trust the pilots in what they are saying: the MAX is not inherently unstable, but some groups of pilots were kept in the dark(ish?) about the MCAS.

If they were kept in the dark it wasn’t by Boeing. It’s not like Boeing omitted parts of its manual to hide a design. Individual airline training programs didn’t inform their pilots. Boeing produces the flight manual and airlines teach their pilots what they feel is relevant out of it. Same with maintenance training. Airlines don’t teach the manual line by line, just the parts they think need to be highlighted.

Bottom line is Boeing doesn’t teach pilots how to fly planes. Individual airlines teach their pilots how to fly. If UA taught their pilots and AA and WN didn’t, it doesn’t mean Boeing withheld information. It means UA has better training.
 
B737900ER
Posts: 1028
Joined: Thu Aug 31, 2006 10:26 am

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 4:23 pm

kalvado wrote:
Would you also agree that Any airframe that is flown in an uncertifiable condition is a step too far?

Is the MAX not certified?

MCAS didn’t cause the plane to crash. The pilots untrained response to it cause the crash
 
N212R
Posts: 210
Joined: Wed Dec 14, 2016 5:18 pm

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 4:39 pm

AvObserver wrote:
Again, all of the facts are not in so it's still way to early to make such conclusions. You assume MCAS is needed to mitigate stability issues. How do you know why MCAS was added? Do you have a mole working at Boeing? And as for your definition: "If it does not return from a non-stalled and within envelope positive angle of attack then it is longitudinally statically unstable by standard definitions of flight dynamics." Do you know for certain this is what happened? Quite frankly, when you say don't take the pilots' word over an engineer's word, what do you know about the engineering of this airplane? Have the engineers come and indicted this design for instability? One thing at least I'd agree on, the MCAS itself may need to be fixed and that is a design issue, albeit probably one that won't take a great deal of time to remedy once they determine how the AOA sensors may have tripped it up. And it's still entirely possible that Lion Air's maintenance may have been complicit in the crash although, heaven forbid, I'm not ready to pronounce them guilty either. Boeing may have a faulty FCS though that too has yet to be proven and there's no denying they erred mightily in not properly announcing and documenting it for the pilots. That error is likely worth a big upcoming fine and possible loss of near-term sales campaigns but the pilots, assuming they're not imposters, are saying the MAX is stable in flight. So as I see it, you too are making a broad assumption which is a bridge too far. Perhaps you too could post some intricate data on just why the 737 MAX is "longitudinally statically unstable" and prove just why all of those assumed MAX pilots are so wrong when they insist it is stable. Enlighten us all!


"Thou doth protest too much, methinks"
 
fsabo
Posts: 197
Joined: Fri Dec 04, 2015 8:41 pm

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 5:59 pm

B737900ER wrote:
kalvado wrote:
Would you also agree that Any airframe that is flown in an uncertifiable condition is a step too far?

Is the MAX not certified?

MCAS didn’t cause the plane to crash. The pilots untrained response to it cause the crash


A single sensor failure caused the aircraft to pitch nose down towards the water. The pilots handled the situation poorly and failed to stop the automation causing the crash. Could the pilots have done a better job and averted the crash? Absolutely. Is MCAS a shitty design? Absolutely. Did the swiss cheese holes line up? Yes. Apparently boeing is not responsible for their swiss cheese hole because there are other holes.
 
dakota123
Posts: 233
Joined: Wed Aug 30, 2006 11:03 pm

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 6:56 pm

WIederling wrote:
AvObserver wrote:
And you have the nerve to say that the opinions of MAX pilots who've chimed in here have no relevance. .................

Even longer lament.
Pilot opinion is worthless as they see the basic airframe wrapped by various enhancing systems ( including MCAS ).
Additionally they did not even know about MCAS.

Then it is not about complex computations or deeply fractal analysis.
It is all in the open.
MCAS appears to be designed to keep the plane below a distinct positive pitch up angle.
( in a rather anal retentive way )
That indicates that the stable range of attitudes ends there.
A stall recovery is deemed very difficult or even impossible.
IMU certification requirements do not allow this situation.
you can have relaxed stability ( but only in cruise?) but not positive feed back.


If that were the case, there's no way it would trim at the rather leisurely rate of 0.27 deg/sec. It would damn well shove the nose down by some method other than trim. And it wouldn't pause for five seconds when countermanded. Fice seconds is an eternity in a stalled or nearly stalled condition.
“And If I claim to be a wise man, well surely it means that I don’t know”
 
kalvado
Posts: 1878
Joined: Wed Mar 01, 2006 4:29 am

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 7:22 pm

dakota123 wrote:
WIederling wrote:
AvObserver wrote:
And you have the nerve to say that the opinions of MAX pilots who've chimed in here have no relevance. .................

Even longer lament.
Pilot opinion is worthless as they see the basic airframe wrapped by various enhancing systems ( including MCAS ).
Additionally they did not even know about MCAS.

Then it is not about complex computations or deeply fractal analysis.
It is all in the open.
MCAS appears to be designed to keep the plane below a distinct positive pitch up angle.
( in a rather anal retentive way )
That indicates that the stable range of attitudes ends there.
A stall recovery is deemed very difficult or even impossible.
IMU certification requirements do not allow this situation.
you can have relaxed stability ( but only in cruise?) but not positive feed back.


If that were the case, there's no way it would trim at the rather leisurely rate of 0.27 deg/sec. It would damn well shove the nose down by some method other than trim. And it wouldn't pause for five seconds when countermanded. Fice seconds is an eternity in a stalled or nearly stalled condition.

Do you have something better to add to the discussion than arguing with well established facts? It was said more than once that MCAS role is exactly that - prevent approaching to stall and upset. Why Boeing chose to do it the way they did, rates, times... Those who know it are not allowed to talk about it.
 
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glideslope
Posts: 1547
Joined: Sun May 30, 2004 8:06 pm

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 8:08 pm

kalvado wrote:
glideslope wrote:
B737900ER wrote:
Any airframe that is flown in an unairworthy condition is a step too far. Lion air pushed the pencil whip limit and got bit. Any flight control system on any aircraft that is flown around broken is dangerous regardless of training and design. Everyone wants to blame the design, but had lion air made an actual attempt at repair and repair confirmation we wouldn’t be having this discussion.


I could not agree more strongly.

Would you also agree that Any airframe that is flown in an uncertifiable condition is a step too far?


In this incident my opinion is based on my knowledge of that region and carrier. It is my opinion that any aircraft operated by LNI could have been subjected to being cleared for flight when it should have been taken off line. In my opinion I have no reason to not fly a Max with a carrier that follows procedures, and has the correct training/maintenance procedures implemented as required. The Max is not a step too far. That is my opinion only. I have no insight into the actual incident other than what is in print. If you offered me a year of free travel on LNI, I would decline. Regardless of the airframe type.
To know your Enemy, you must become your Enemy.” Sun Tzu
 
kalvado
Posts: 1878
Joined: Wed Mar 01, 2006 4:29 am

Re: Did the 737 MAX go one step too far?

Fri Dec 14, 2018 8:10 pm

glideslope wrote:
kalvado wrote:
glideslope wrote:

I could not agree more strongly.

Would you also agree that Any airframe that is flown in an uncertifiable condition is a step too far?


In this incident my opinion is based on my knowledge of that region and carrier. It is my opinion that any aircraft operated by LNI could have been subjected to being cleared for flight when it should have been taken off line. In my opinion I have no reason to not fly a Max with a carrier that follows procedures, and has the correct training/maintenance procedures implemented as required. The Max is not a step too far. That is my opinion only. I have no insight into the actual incident other than what is in print. If you offered me a year of free travel on LNI, I would decline. Regardless of the airframe type.

Thank you. But that was a "yes" or "no" question. So?

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